Comments: An oriented meteorite
with attractive deep pitting and only minor amounts of corrosion.

Background: Meteorites are solid
objects that fall to Earth from space. Since meteorites are
among the oldest objects that exist on Earth, they provide
valuable clues as to the origin and evolution of our solar
system and planet. The Campo del Cielo meteorite shown above
is a nice example of a well-preserved iron-nickel meteorite
that has suffered little in the way of corrosion.

California Minerals

At the Science Education Center, a great deal
of effort has gone into acquiring a large number of local minerals,
and historical items relating to California’s early history.
This collection is always changing due to frequent sales and
acquisitions. Two such items are shown above and are described
as follows:

Left photo: Azurite and malachite
together (gem quality and not stabilized) from the Copper
World Mine (San Bernardino County). Note: A repaired specimen
from the Dr. Ralph Pray collection.Price: $300

Right photo: A 3 pound piece of botryoidal
nephrite from Jade cove, California. This 6 inch long cabinet
specimen has good color and some translucence.Price: $295

Comments: A colorful drusy chrysocolla
specimen on a malachite matrix. The drusy chrysocolla portion
can be cut from the specimen and used in jewelry.

Background: Malachite derives its
name either from the Greek word malachos (for soft) or from
the mallow by virtue of its green color. Malachite is an important
copper ore and forms in the upper oxidized zones of copper
deposits. When free of matrix, malachite is often suitable
for cutting and is used as a valuable ornamental stone.

Gem
Azurite

Comments: This azurite specimen contains
over 2,500 grams of gem quality azurite which can be used
as a museum displayable cabinet specimen or as cutting rough
for jewelry. Unlike most azurite that is on the market, this
piece has not been chemically stabilized or enhanced with
waxes or resins.

Background: Both malachite and azurite
are found in the upper oxidized zones of copper deposits and
are important indicators of copper. Azurite is less chemically
stable than malachite and tends to slowly covert into malachite
over time. This can be observed in malachite pseudomorphs
after azurite which have the crystal structure found in azurite
specimens and the green color of malachite.

Price: With the exception of the small pieces
in the lower right photo (typically $5 to $15 each), most
specimens are priced in the $40 to $150 range. Larger specimens
(not shown) are costly and are a few hundred dollars. The
malachite ashtray (lower left photo) sold for $120.

Comments: Some very colorful
combinations of malachite and chrysocolla have been mined
recently in the Congo. The specimens shown here were part
of a larger group (about 10 specimens) that we had recently
purchased. Unfortunately, they sold even before we could get
the photos on line. As a result, the specimens shown above
should be characterized as a representative sample of the
material that we can get from time to time.

To satisfy the needs of our mineral enthusiasts, we have
over 100 specimens of copper minerals to choose from and have
ready access to a number of mining localities. As always,
it is best to call in advance to get a latest update on what
is available.

Malachite
Stalactites

Dimensions: Various sizes (click on photo
for larger image and detailed size comparison)Price: Variable depending on shape and quality.
Most of the African stalactites and botryoidal masses are
around $20 - $40 per pound. Perfect specimens with extraordinary
shapes (and few surface scratches) command higher prices and
are individually priced. The material from Bisbee generally
goes for around $100/pound. The best material from Bisbee
is priced individually. Fine specimens are costly.

Comments: These specific specimens
have already been sold. We have a good collection of botryoidal
malachite masses and stalactites in stock. The specimens shown
above are a representative sample of the quality available
at the Science Education Center.

1 to 4 inches in diameter. Larger sizes are available
but are less abundant.

Prices:

Our smallest ammonites available (most
economical in price) are about ½ inch to ¾
inches across and are currently priced at $2/slice. Larger
sizes are available and are priced at around 10 cents
a gram, or around $100/kilogram. Based on these prices,
museum quality items (as nice as those pictured in textbooks
and several inches in diameter) can be purchased for around
$30 - $75 dollars per slice. Occasionally we will have
even larger ones (well crystallized and almost a foot
in diameter with spectacular colors) for around $200 per
slice. The largest ones are used in the science museum
on wheels presentations and are occasionally sold as we
obtain duplicate material.

Comments: The Science Education
Center features over 1,000 cut and polished slabs (500 pairs)
of very well preserved fossilized ammonites. Most of the ammonites
have a complete outer shell, and show in great detail each
of the chambers that the living creature has occupied. Many
of the chambers have hollow portions filled with calcite crystals
(yellow) and iron rich impurities (red). Each ammonite is
unique in its spiral detail, extent of chamber preservation,
and mineral contaminants that are responsible for the vivid
yellow and red colors.

Background: Ammonites were abundant
members of the mollusk family in the Mesozoic era, some 100
million years ago. The present-day nautilus may be a descendant
of these long-extinct marine animals. Ammonites built their
multi-chambered shells out of calcium carbonate. Through the
millennia, this originally fine-grained material has been
recrystallized until now it is virtually a marble yet still
preserving the shape and pattern of the dead animal's house.

Services: The growing popularity
of ammonites in jewelry (earrings and necklaces) has led to
an increased demand, which occasionally outstrips the available
ammonite supply. To meet the needs of the jewelry market,
we are offering to drill small holes in thin slices to accommodate
chains, bezels and other jewelry attachments. The cost of
this service (for ammonites purchased from the Science Education
Center) is only $1/hole.

Cut Stones

Carat size: Our large specimen stones usually
range from a few carats to several thousand carats. We have
a smoky quartz (sale pending) that weighs approximately 4,750
carats. It was so big that the GIA in Carlsbad had to weigh
it on their postal scale instead of their standard gem scale.
Price: The specimens shown above have already
sold and typically sell for around 1 to $4/carat.

Comments: The Science Education
Center generally does not specialize in cut stones. There
are a large number of companies that specialize in color stones
and some have very good prices. From time to time, we pick
up a super deal and will pass it on to our customers. The
specimens shown above were part of such a purchase and are
a representative sample of the size and quality of the material
that we occasionally have in the 1 to $4/carat price range.
Usually after the Tucson show, a few cut stones will be acquired,
either individually or as part of a larger acquisition. Give
us a call in mid February to see what we have picked up. Specific
requests for items should be made by early December.

Crystallized
Metallic Minerals

Comments: A well crystallized
Bolivian cassiterite on a matrix of quartz crystals. The smaller
specimen to the right of the Bolivian cassiterite is a one
pound single crystal of cassiterite from China. This purplish-brown
specimen is from the collection of Clifford J. Krueger, and
is priced at $400.

Comments: Native copper, copper
carbonates (malachite and azurite), natural alloys of copper
and silver, and copper combined with other minerals (such
as calcite) are a favorite at the Science Education Center.
We have over 100 specimens of copper minerals to choose from
and have ready access to a number of mining localities. As
a result, we generally do not run out of copper specimens.
As always, it is best to call in advance to get a latest update
on what is available.

Background on Copper: Occurrence
in the earth’s crust: 70 parts per million; also present
in seawater: 0.001 – 0.02 ppm. Two naturally occurring
isotopes: 63 (69.09%), 65 (30.91%); nine artificial isotopes:
58 – 62, 64, 66-68. One of the earliest known metals.
Besides native copper, which can be as high as 99.9% pure,
the element occurs as two principal classes of minerals: sulfide
ores and oxide ores. The principal sulfide ores are calcocite
(Cu2S), calcopyrite, or copper
pyrites (CuFeS2), and covelite
(CuS); the principal oxide ores are cuprite and tenorite,
and the major carbonate is malachite (Cu2(CO3)(OH)2).
About 80% of the present annual copper production (around
3,000,000 tons per year) is from the sulfide ores.
A trace element essential to many plants and animals. Occurs
in biological complexes such as pheophytin (analog of chlorophyll),
hemocyanin, tyrosinase and ceruloplasmin.

Uses: Manufacture of bronzes,
brass, other copper alloys, electrical conductors, ammunition,
copper salts, works of art and in coinage. We should note
that the copper coins of today are mostly zinc. After the
year 1982, the United States Mint changed the composition
of the U.S. cent to 97.5% zinc and 2.5% copper. These zinc
cents have a coating of pure copper and were designed to reduce
the cost of coinage and save the critically important element
for more pressing needs. Zinc is not only less expensive than
copper, it is also about 100 times more abundant than copper
in the Earth’s crust.

Amethyst

Comments: The Brazilian and Uruguayan
amethyst can generally be distinguished by the intensity of
the color. The Uruguayan specimens tend to have smaller crystals
and a much deeper purple color than their Brazilian counterparts.
The deeper colors are also more highly sought after. As a
result, the prices tend to be considerably higher for the
Uruguayan material. We have many small pieces for under $15
and a few museum items (on occasion). Our current giant is
98 pounds ($675) and has a large calcite crystal extending
through the center of the druse.

Quartz Crystals from
Brazil

Left Photo:Locality: BrazilComposition: Quartz with inclusions of chlorite
and rhodonite

Dimensions: 5 inches tall and 4 inches
in diameterPrice: $395

Comments: A fascinating specimen
of chlorite and rhodonite entombed in rock crystal.

Note: The crystal faces have
been cleaned up a bit to bring out the beauty of the multiple
mineral inclusions. Finally, some of the internal inclusions
display very colorful irises, which are visible in natural
and artificial light.

Comments: We have a large quantity
of well-crystallized pyrites for the beginning collector.
Children can measure the size of each crystal face as well
as the angle between crystal faces. By finding the sum of
all crystal face measurements and dividing by the total, the
student can determine the average value for the crystal face
size. Students can then do the same thing for the angles between
crystal faces and check to see which one varies more, the
crystal sizes or the angles between crystal faces.

Fluorescent Minerals

The Science Education Center has over 2,000 pounds
of fluorescent minerals composed mainly of willemite (fluorescent
green) and calcite (fluorescent red). Many of the specimens
contain rare and colorful minerals such as zincite and the typical
black franklinite. Scarce fluorescent minerals at the Science
Education Center (several in the photo above) include crystals
of the following:

Scheelite (fluorescent blue)

Hardystonite (fluorescent purple)

Anglesite and cerussite (fluorescent orange)

Halite (fluorescent red)

Sapphire (blue and red fluorescence)

Zircon (orange fluorescence)

Adamite (lemon-yellow)

Prices: We obtained a large quantity of
fluorescent minerals at very reasonable prices. As a result,
most specimens can be obtained for around 2 to 6 dollars per
pound. Cut fluorescent spheres are remarkably attractive and
command prices in the $100 - $600 range. The rarer mineral
crystals (not massive material) are individually priced and
range from a few dollars to several hundred dollars for museum
specimens. The items shown in the photograph contain both
fluorescent crystals as well as the typical massive material,
which is rather modestly priced.

What is fluorescence: With the exception of the rare fluorescent
minerals, most of the fluorescent material in the Krawitz
Collection comes from the contact metamorphic zinc deposits
at Franklin and Ogdensburg, Sussex County, New Jersey. This
great zinc deposit has yielded a fortune in zinc for the New
Jersey Zinc Company, and a bonanza of fluorescent material
for collectors and museums.

The main fluorescing minerals in this great zinc deposit
are willemite (Zn2SiO4)
and calcite (CaCO3). Willemite
will fluoresce an eerie greenish yellow and calcite will fluoresce
a bright red. The fluoresence is due to the ability of electrons
in these minerals to go to a higher energy state when illuminated
by higher energy light, which in this case is short wave ultraviolet
light (254 nm). When the excited electrons fall back to the
lower and stable energy state, energy in the form of visible
light is emitted. Some of the finest fluorescence is found
in the fluorescent spheres, which are available for viewing
and sale at the Science Education Center.